This invention relates to medical devices for injecting living bodies and, more particularly, to safety features incorporated therewith. In particular, it relates to alternate constructions and methods of manufacture for retractable protective sleeves used over the needle of syringes and the like.
In U.S. Pat. No. 4,998,922 by Thomas C. Kuracina entitled SAFETY SYRINGE CAP MINIMIZING NEEDLE-STICK PROBABILITY which issued Mar. 12, 1991, a safety device for hypodermic needles and the like is shown. The inventions shown hereinafter are improvements thereto by inventors including and/or working with Mr. Kuracina. In the interest of simplicity herein, the teachings of that patent are incorporated herein by reference and the discussion of the background art will be kept to a minimum.
A typical prior art hypodermic syringe 10 as shown in FIG. 1 includes a barrel 12 having a moving plunger 14 therein. A needle 16 having a sharp beveled tip 18 extends from the end opposite the end of the barrel 12 into which the plunger 14 is inserted. The needle 16 is covered by a removeable cap 20 for safety purposes. The problem to be solved and avoided is the accidental sticking of users of the syringe 10 by the tip 18 after use where the tip 18 may carry body fluids containing agents of hepatitis B, AIDS, and the like. Accidental needle stick is a very common problem in the health care industry and besides the risk of serious illness or even death as a result thereof, the insurance industry spends over a billion dollars a year in the testing of individuals who have been subjected to post-use needle stick.
The 1979 patent of Alvarez proposed a retractable plastic protective sleeve 22 as depicted in FIGS. 2 and 3. The Alvarez sleeve 22 has an inner hub 24 which fits around the base of the needle 16 and an outer hub 26 through which the tip 18 passes. The inner and outer hubs 24, 26 are connected by curved slats 28. When the needle 16 is to be inserted into the body of a patient, the force required to move the sleeve 22 from its extended position of FIG. 2 to its retracted position of FIG. 3 is as depicted in the graph of FIG. 4. Thus, there is really no actually safety from a large variety of ways in which accidental needle stick takes place. Even if the sleeve 22 fully extends after use, a slight blow against a user or observer in the area will cause the sleeve 22 to retract and the tip 18 to stick the unfortunate person.
A Kuracina protective sleeve 30 in a preferred embodiment is depicted in FIG. 4. The slats 28' are transversely curved to cause a high degree of force to be required to move the protective sleeve 30 from its extended position covering the tip. Moreover, a spring-biased locking collar 32 is added over the protective sleeve 30, which all but prevents the protective sleeve 30 from moving from its extended position covering the tip. The locking collar 32 must be moved from its locked position to a retracted, unlocked position before the unique deformation qualities of the sleeve 30 take effect. After use, the locking collar 32 springs back to its locked position. Thus, in virtually all "accidental" contact with the tip end of a hypodermic syringe, actual penetration by the tip should be prevented.
As originally disclosed, the Kuracina protective sleeve is shown as a unitary device made in a single injection molding process and assembled over an associated needle from the tip end of the needle. The inventions described hereinafter are intended to provide alternate methods of constructing and manufacturing the Kuracina protective sleeve to attain certain benefits to be described and as will be recognized by those skilled in the art.
Other objects and benefits of the inventions disclosed herein will become apparent from the detailed description which follows hereinafter when taken in conjunction with the drawing figures which accompany it.